About those WAC Bennett Dam repairs…

Back in November, I saw a notice in the paper about a BC Hydro application to the BC Utilities Commission for rip-rap repairs on the WAC Bennett Dam, and blogged about the complete and utter hypocrisy of this in relation to the Site C dam exemption: https://lailayuile.com/2015/11/30/a-river-runs-through-it-the-hypocrisy-that-is/

But as the province continued to move full steam ahead on Site C, a multi billion dollar project the government exempted from that very same process required to do repairs on the WAC Bennett dam, something just didn’t feel right. I couldn’t put my finger on it but something brought me back to take another look at those Bennett Dam repairs.

What I found was stunning in my opinion, and had received very little press other than a story in the Globe and Mail shortly before Christmas 2015-from the looks of the response to that,few had even noticed it. That lead me back to the BC Utilities Commission for another look at the documents being presented by Hydro during this regulatory review and what I found, was concerning for several reasons: https://lailayuile.com/2016/03/10/bc-hydro-responses-to-bc-utilities-commission-raises-new-questions-over-wac-bennett-dam-repairs/

The repairs were in fact extensive and long overdue.


To me it seems a very calculated risk to have allowed these conditions identified in 1998, to have gone so long- particularly when you consider the new questions raised by the utilities commission with respect to two other issues identified by the experts that had not been addressed yet.

The BC Utilities Commission had more questions for BC Hydro following that last round of questions and last week BC Hydro’s response was submitted- this is the full response package from BC Hydro that I will summarize below :

The response is long, but includes a follow up report from the same expert review panel – completed in March of this year – that identified the conditions,concerns and risks back in 2012. The panel made a number of recommendations to BC Hydro at that time including the following- it is point 5 that the BC Utilities Commission has been asking about:


Points of interest from the review panel:

Pg 19: 2.2 Rip-rap repair: 

Documents have been issued which will lead to the appointment of a contractor to complete the repairs to the rock face over three seasons when water level is low. The possibility exists that stripping the rip-rap may destabilize the upper slopes and measures must be in place to address this situation


Pg33: 2.6  3D CAD & GIS models:

The Sonar survey has identified two interesting features, one which looks like a shallow landslide on the upstream slope of the embankment below the rip rap; and another localised depression near where the embankment abuts the canyon wall. The reasons for these are being investigated by BC Hydro
Pg 46: 5.3 Monitoring Measurements at Sinkhole #1
There is a large number of monitoring installations and instruments in Sinkhole 1 and in the immediate vicinity of the sinkhole. The diameter of the heavily disturbed column of soil down to about 100-ft is estimated to be about 10-ft, and there is more or less disturbed material in a circular column 26ft in diameter.The sinkhole goes deeper than that, but the estimated diameter is significantly smaller.
Not all of the local instrumentation is essential or very useful, and BC Hydro is reviewing the situation.A review is especially important at this time when plans are being made for the required construction work related to new layer of riprap to be placed on the upstream side of the dam. Heavy equipment,transportation and construction work will affect the monitoring activities at Sinkhole 1, and the instruments considered valuable for future monitoring must be protected to remain functional.
A draft of an Inter-Office Memo (dated 18 November 2015) was made available to the EEP during the present meeting. The EEP has not had the time to study the Memo, but it seems to give a detailed review and analysis of the situation and the possible actions to be taken.
Pg 48: Summary of Conclusions and Recommendations

-The upper part of the dam is vulnerable to deformation and transverse cracking under seismic loads, in particular in the areas affected by the two sinkholes, and is also vulnerable to seismic loads at the Spillway-Embankment interface

-there is a low likelihood that given the earthquake occurs the induced cracks in the top of the dam will penetrate as deep as to full supply level where the dam is very wide. However as discussed in Section 3.4.3 the deformations  and cracking are difficult to model because of the complex 3D geometry and the difficulty in modelling the pore pressure build up and loss of stiffness in the loosened fill around Sinkhole #1 under seismic  loading.

– The EEP is concerned that the time for development of internal erosion from initiation to breach has been overestimated in a number of PFM,  ( Performance Failure Models) and that in reality, concentrated leak erosion may  develop in hours or days, not months and years as assumed. This may have important implications for how the risks are managed.

– The EEP made a number of recommendations for BC Hydro to further investigate  certain technical matters as well as reminders for earlier recommendations made in 2012, that Hydro has not yet completed.
Long story short, BC Hydro must now use a ‘risk-informed’ approach to doing further upgrades or repairs, something the BC Utilities Commission has questioned with regards to the vulnerability to the upper portion of the dam. And at this point in time there is further testing to be done before any decisions are made regarding possible remediation:

It’s all fine and dandy, but the question remains why these situations have been left so long by BC Hydro before being investigated and acted on,particularly since we know now that fracking causes earthquakes in northeastern BC.The documentation clearly shows these issues were identified as far back as 1998. And the extensive and pertinent questions of the BC Utilities Commission clearly show the value of their work in reviewing Hydro projects, which is why it remains a travesty that Site C was exempted.

The people of BC will never have the security these reviews offer as the only check and balance to BC Hydro. As Premier Clark forges ahead to get Site C past the point of no return, even contracting turbines before ground has broken, WAC Bennett dam sits waiting for repairs even as BC Hydro gets ready to borrow more money to pay the government dividends…

Kind of makes you wonder how effective & visionary the decision making at BC Hydro really is, doesn’t it? And why the Energy Minister Bill Bennett and Premier Clark would  applaud such fiscal irresponsibility at all.







13 thoughts on “About those WAC Bennett Dam repairs…

  1. This gets to the heart of the problem. My question is, do any of the failure models identify which populations downstream are being put at risk? Also, investing billions into Site C without mitigating upstream risks seems like criminal behavior to me. Thoughts?


    1. The reports state the dam was well constructed-for its time. I have no fear that the dam is in danger of breaching unless the circumstances described occur,which are said to be unlikely. The issue for me is that it is considered an extreme consequence dam and I question why this was all left so long?

      It is not simply an informed risk, it is a calculated risk that counts on no earthquakes of sizable magnitude and duration or high wind events during high water levels. The work has to be done during low water levels over a period of years on the rip-rap alone,but the concern over the upper portion of the dam is why the BCUC was asking these other questions.The expert report recommended finding a way to address all three risks. BC Hydro is not committing to that nor have they completed all the recommendation the expert panel asked of them in 2012.

      Quite frankly, what’s the hold up?

      Were these repairs not done as a capital cost saving measure ordered during the 2011 BC Hydro review? Why did BC Hydro not act on this until Site C was underway? What is the state of the Mica dam also referred to in this new report?

      And who exactly bears the responsibility for making these ‘informed risk’ decisions in the event the unlikely happens? We had a freak severe windstorm here last summer with near hurricane force winds that took out power for days in Metro Van and the island. There are fracking operations not that far from WAC Bennett Dam.

      I just can’t understand why heads aren’t rolling over this.

      Thank God the BCUC is all over it asking questions.None of this would have been known if Hydro didn’t have to put forth an application on it.

      That the government exempted Site C from this same scrutiny is a breach of public trust in my opinion.This is an excellent example of what they do and why they do it. The public has no other recourse-none of the other reviews done of Site C looked at things like this,the cost,or if it is in the best interests of British Columbian ratepayers.


  2. Have any of Chrispy’s operations proven successful? Can’t think of one. Why should Site C prove any different. I wouldn’t wish for a failure of the WAC Bennett dam, but it would sure wreck havoc on Site C as it thundered through the downsteam territory. Think Mount Polley was bad? You ain’t seen anything yet!


  3. The only reason to explain the urgency to build site C, other than the fact that the Columbia River Treaty is coming to an end in 2024, is that the WAC Bennett dam water level has to be dropped down to ZERO to do a major fix rather than a band-aid approach before a 8.0 tremor comes along.


  4. The dams, when they were built, were built to last, as it was understood at the time. At the time things like maintence were done. The fact dam failure could kill taxpayers, citizens, etc. its a chance the B.C. Lieberals are willing to take. Hey, they’re only taxpayers and we have our friends to look after.

    The B.C. Lieberals in my opinion have never cared about human life outside of its own circle. el gordo didn’t care when he started the largest mass firing of female workers in Canadian history; they didn’t care when 86 people died of il dificile at Bby, General in 2 1/2 yrs. the B.C. lieberals don’t care we have the lowest min. wage and have had the highest rate of child poverty in 14 of the past 15 yrs. they didn’t even seem to care when 4 children died in care. So if they don’t care about all of the above, why would they care if the dam broke and people died. Its just one of those things and in the meantime, hell they took care of their friends.

    We have only to look at the current situation with schools boards trying to make ends meet. So if that doesn’t bother Christie and crew, why would they care if a dam broke?.

    500K people don’t have family doctors and you can bet more than one person has died because of it. still Christy and her crew haven’t improved things. So why would anyone thing she would care about a dam breaking?

    Just because some of us care about the people of this province doesn’t mean the politician do.


  5. With the seeming likelihood of the Site C project facing a BCUC review under an NDP/Green coalition, this would be an appropriate time to strongly suggest that public safety upgrades to the existing dam take priority over any addition to BC’s hydroelectric generation capacity.

    Even a partial failure of the WAC Bennett dam would endanger the inhabitants of Hudson’s Hope and the surrounding area along the Peace River, potentially cause cause costly power shortages, and render the work currently being performed to construct another dam not only a loss, but a liability as the disturbed landscape would likely carry far more sedimentation downriver with commensurate impact on the life systems within it.

    The distance from the current site and work camp to the WAC Bennett would not be prohibitive for daily travel, the skill sets of those already working would be easily transferable to working on the needed repairs, and this would allow for a cessation of work upon Site C while productively providing continuity of employment for the work force lodged near Ft St John.

    A less tangible but real benefit to that would be the creation of a leeway period for the workers if the BCUC review appeared to be leaning towards a negative judgement regarding the advisability of Site C at this time, and the relative easement of the consciences of those who might have doubts as to their employment being “right livelihood”, a factor that is far too often ignored in favour of simple monetary considerations.

    “No, BC Hydro, you cannot have another dam, you can’t take care of the ones you already have.”


    1. If you take a look here, there is extensive writing on WAC Bennett Dam repair plans that were submitted to the BCUC in fall 2015… long after they were identified in 1998.


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